My partner would like some killifish, just the small ones, we have the 100litre for the females & its the only place the killifish can go if we got some, would it work? my females are quite tollerant & live with platys, gourami & tetras all fine......so......? what u think?

Hello
Going back about 20 years ago I did a lot of "Killi" breeding.....at one time I had over 100 shoe boxes going with fish and fry....if there is one thing I learned it's that they are nasty if another fish invades their space....If your Betta gets to close it's gonna have some missing scales and ripped fins...however if you have enough plants in the tank they will get used to each other after a fashion...if you put them together watch them for at least an hour and have a net handy...
Bad Fish